You do you, but not really. You need to remember which colour the book is to find it. Doesn't work for daltonians or colour blind people. Another examples, Numenera books are not the same colour. The player book is mauve while the setting/gm book is teal. What do you do then? 3.5 DMG is blue but the PHB and monster are red and brown. Where does the blue DMG go?Some people order them by color, as they feel it's clearly the easiest and most effective way to organize books by far.
I'll raise. I know someone who has RPGs books everywhere, on his wall to wall bookshelf, on the kitchen table, on the sofa, on the lazy-boy, on the toiler tank, in his work office, in the corridor which only 18" wide because of books shelves. He lives by himself. It makes it hard to visit or play at his house. He has to create stacks of books next the kitchen table so we can play. He calls it snowblowing the books. I haven't been there since Covid started.Organized? LOL
The bulk are in storage bins in my bedroom closet, and the most current ones I'm still browsing are scattered between my end-table by my bed, and bookshelves in my son's room and our living room.
If I lived by myself, I'd have a studio apartment with minimalistic furnishings, with one of the only flourishes a nice bookcase with all my RPG books prominently featured.I'll raise. I know someone who has RPGs books everywhere, on his wall to wall bookshelf, on the kitchen table, on the sofa, on the lazy-boy, on the toiler tank, in his work office, in the corridor which only 18" wide because of books shelves. He lives by himself. It makes it hard to visit or play at his house. He has to create stacks of books next the kitchen table so we can play. He calls it snowblowing the books. I haven't been there since Covid started.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.